If we choose to live near convergent plate boundaries, we can build buildings that can resist earthquakes, and we can evacuate areas around volcanoes when they threaten to erupt. Yes, convergent boundaries are dangerous places to live, but with preparation and watchfulness, the danger can be lessened somewhat.
Nitrification, as stated above, is formally a two-step process; in the first step ammonia is oxidized to nitrite, and in the second step nitrite is oxidized to nitrate. Different microbes are responsible for each step in the marine environment.
3. Shorter Surface Intervals. A diver using nitrox absorbs less nitrogen for a given depth and dive time than a diver using air. This means that diving on nitrox you have less nitrogen to off-gas during a surface interval, which can shorten the required surface interval drastically. Get Nitrox Certified and Stay Down Longer.